1. Field of the Invention
The invention is related to the field of communication networks and, in particular, to distributing the tasks of providing value-added services for calls in a VoIP network among multiple network nodes in the VoIP network. More particularly, the tasks of providing services are distributed among VoIP endpoints, media gateways, or other network nodes, instead of being provided by one or more centralized media servers.
2. Statement of the Problem
Voice over Internet Protocol (VoIP) is a technology used for the routing of voice conversations over a data network using Internet Protocol (IP). The data network may be the Internet or any other IP-based network, such as an enterprise intranet. VoIP networks are typically viewed as a lower cost alternative to traditional public switched telephone networks (PSTN).
A typical VoIP network is comprised of one or more application servers, one or more centralized media servers, one or more media gateways, and a plurality of VoIP endpoints. The application server provides call processing within the VoIP network. The media server includes media resources that are adapted to provide value-added services for calls in the VoIP network, such as playing announcements, compression/decompression (CODEC) conversion, DTMF digit collection, conferencing, ringback tones, advertising, etc. The media gateway is adapted to interface the VoIP network with a PSTN. The VoIP endpoints are network elements used to originate or terminate a call over the VoIP network, such as a VoIP phone, a PDA, a computer having VoIP capabilities, etc.
The following illustrates how a VoIP network serves a call. One of the endpoints originates a call by transmitting a signaling message (e.g., a SIP INVITE message) to the application server. Responsive to receiving the signaling message, the application server performs call processing to provide standard VoIP services and value-added services for the call, much like a switch provides telecom services and value-added services in an intelligent network. To provide value-added services, the application server processes service triggers for the value-added services to determine if a trigger condition is detected. If a trigger is detected for one or more of the value-added services, then the application server suspends call processing and transmits a request for media resources to the media server. The media resources are the facilities that provide the proper service. Responsive to receiving the request, the media server assigns the proper media resources to provide the value-added service for the call. The media server then transmits a response to the application server indicating that the service has been provided, and the application server resumes normal call processing to handle the call. A similar process is performed so that the media server may provide value-added services for other calls in the VoIP network.
One problem with present VoIP networks is that the media server(s) is responsible for providing the value-added services for the entire VoIP network through its media resources. As a result, network operators estimate a maximum media resource demand in the VoIP network for providing the value-added services during peak times, and engineer the media server or media servers to handle the maximum media resource demand. This may mean engineering the media server or media servers with high performance hardware platforms, such as high speed CPUs, large memory, and fast network interface cards (NIC), in order to handle the maximum media resource demand. However, a VoIP network rarely operates with enough traffic to reach the maximum media resource demand. Thus, the media servers may be engineered with a processing capacity that far exceeds the average media resource demand in the VoIP network, which is a waste of network resources.